The study of the luteotrophic (LH) and luteolytic agents such as steroids and prostaglandins will be done. We will investigate their effect on the modulation of the receptor sites of LH in luteal cells maintained in tissue culture using as a binding assay the one described for the interaction of LH and hCG with its receptor site in luteal cells. The effect of the ovarian growth factor on the rate of luteal cell division and its physiological significance will be studied. This will also cover the binding characteristic of the OGF to the luteal cells to see if a modulation of site during the phase of differentiation of the luteal cells does exist.